sbs 2003 flashing taskbar and desktop icons

This is my problem I'm running sbs 2003 and the taskbar and desktop icons will flash every 5 sec. At first my Task manager was also grayed out so I could not enter it. After going into regedit and changing the value back to 0 I can now enter Task manager. It seems that explorer.exe is restarting every 5 sec. I've tried the cleaning prod. that is recommended but either they don't work for sbs 2003 or they don't find anything. When I start this computer in safe mode the problem stops.

I think someone used this computer to surf the web and picked up a virus or something. The reason i think this is because when i opened IE I saw an anti-virus button on the tool bar that I did not install. After setting the IE options back to default the button went away and this problem started.

Any help would be great

Thanks John